The present invention relates to devices for temporarily affixing objects utilizing vacuum and in particular to a vacuum distribution manifold apparatus for vacuum tables.
Surfaces capable of affixing an object by vacuum are commonly known as vacuum tables. Prior art vacuum tables commonly have a predetermined perforated region through which maximum vacuum suction force typically is applied to an object that covers at least the predetermined perforated region. The suction force is usually generated by a vacuum pump system. The object becomes thus affixed to the surface while the suction force or vacuum is enabled. Suction force is lost through holes not covered by the object, and thus many techniques have been employed in the prior art to overcome this problem.
One possible solution is to utilize a suction force controlling device such as a Coanda-Effect operated diaphragm device, or a differential pressure valve. This is an inherently costly solution, since one such device is needed for each of the numerous holes of a vacuum table.
Another simple and effective solution is to cover any uncovered region with masks of various shapes. In mass manufacturing processes the objects usually has a constant size, and a custom made mask is therefore commonly utilized.
Another solution is to divide the perforated region into a number of smaller areas so that suction-force can be occluded from those areas not in contact with or covered by the object. Vacuum valves operated by electrically controlled solenoids are widely utilized in industrial vacuum table applications.
It should be noted here that, for ease of understanding the prior art predicaments, the following discussion relates to FIGS. 1A and 1B, illustrations of a 5-area addressable vacuum table. Persons versed in the art will readily appreciated that, for each addressable area, substantially identical subsystems need to be employed.
FIG. 1A is a schematic view of a prior art vacuum table system configuration for directing suction-force to multiple addressable areas 100 of a vacuum table 102. A vacuum pump 104 is coupled to a manifold 106 comprising a predetermined number (2, 3, or more) of ports 108. Each port 108 is coupled to a respective area suction inlet port 110 via a suitable tubing 112. To independently control suction-force to each area 100, each tubing 112 is equipped with an individual shut-off tap 114.
All shut-off taps 114, except a shut-off tap 128, are activated or, deactivated by a vacuum distribution control system 124, thus inhibiting flow of suction force to all undesired areas 100 and enabling all available suction force to a predetermined area 126.
FIG. 1B shows a more detailed schematic view of individual shut-off tap 114, comprising two main components, a vacuum valve 118 and a solenoid 120. Suction force is either allowed to or inhibited from traversing vacuum valve 118 by activating or by deactivating solenoid 120. Solenoid 120, receives an activate/deactivate signal 122 from vacuum distribution control 124 (best seen in FIG. 1A) or any other suitable subsystem.
To achieve a highly precise dimensioning of an active suction area, a substantial number of addressable, small areas need to be controlled by an equal number of manifold ports, tubing, shut-off taps with accompanying devices, electrical control cabling, etc.
Thus, a substantial number of mechanical, electromechanical, power supply, and electrical control devices are needed in order to perform the task of directing suction force to a few areas of the vacuum table. Those versed in the art will readily appreciate that this can result in a multitude of potential sources of malfunctioning.
There is, accordingly, a need in the art for a novel technique for improved suction force directing means, directable in a variable way to a multitude of areas.